Development of lignin based sunblockers for suncreams
Chua, Yun Khim
Date of Issue2016-04-01
School of Materials Science and Engineering
Institute of Materials Research and Engineering (IMRE)
As overexposure to ultraviolet (UV) radiation has detrimental effects to our skins, development of effective sun-cream is essential for protecting our skins against the UV radiation. A promising approach to add-on or further improve the UV protection property of commercial creams will be via incorporation of lignin as it has UV chromophoric groups for UV absorption. Additionally, lignin has aromatic rings of hydroxyl and methoxy groups, providing antioxidant property for reduction of UVinduced skin damages. However, incorporation of raw lignin will reduce shear thinning effect of the creams. Hence, lignin-based grafted copolymers approach was adopted in this project. Moreover, this approach can also enhance the dispersion efficiency of lignin in the commercial creams. Lignin-poly(ethylene glycol) methacrylate (PEGMA) grafted copolymers were synthesised via atom transfer radical polymerisation (ATRP) and characterised by nuclear magnetic resonance (NMR) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Furthermore, they were blended into commercial creams and characterised by UV-visible spectrophotometer and rheometer. Lignin-PEGMA grafted copolymers demonstrated its ability to improve SPF of commercial creams. Additionally, it can provide antioxidant property. Among the various percentages of lignin-PEGMA grafted copolymer incorporation, and feed ratios of lignin to PEGMA, that had been experimented, 10% lignin-PEGMA500 (0.4g : 2g) grafted copolymer (A1) was deemed to provide the best sun-cream performance, especially in Shiseido SPF15 sun-cream. It had improved the SPF from 15.36 ± 2.44 to 38.53 ± 0.26. In summary, lignin-PEGMA grafted copolymers can potentially be incorporated into commercial creams for greater efficacy in UV protection.
Final Year Project (FYP)
Nanyang Technological University